Styrene and other chemicals contained in polystyrene are considered a human carcinogen agent by government agenciesTHE GUARDIAN
Reason #1: Tonnes of EPS pod offcuts are generated on building sites
There are12,500 people waiting in a line, each carrying a block of polystyrene as big as a coffee table and one by one they throw their block of polystyrene into the sea.
If the recent trend of using expanded polystyrene (EPS) in waffle foundations continues, unaware, you too could be one of these people in that row because, unfortunately, also in first world countries such as New Zealand at least 1% of polystyrene from the construction and demolishing business ending up in our seas.
Reason #2: Styrene and other chemicals contained in EPS (HBCD in particular) are considered a human carcinogen agent by government agencies 
EPS typically used for construction applications contains hexabromocyclododecane flame retardant (HBCD).
HBCD has been classified as a Substance of Very High Concern within the European Union due to its persistence, bio accumulative properties, toxicity and long-range environmental hazard if transported. In the successful proposal to list HBCD under the Stockholm Convention on Persistent Organic Pollutants, the Government of Norway submitted:
“HBCD is highly toxic to aquatic organisms, and according to laboratory tests with mammals, it affects the functioning of the thyroid system and liver. There are also indications of effects on fertility and developmental neurotoxicity of mammals. HBCD is according to the available data also transferred from mother to child during pregnancy via blood and after delivery via breast feeding.”
There is a voluntary industry accord in place for HBCD which represents an understanding between signatory companies to move away from HBCD towards alternatives.
The New Zealand Ministry for the Environment is continuing to work with industry to confirm supply settings are right before regulating HBCD which we anticipate will be late 2016 or early 2017. This would include HBCD in building products. 
Reason #3: In many ways EPS is not a sustainable material 
The carbon footprint of EPS is superior than other building materials. Production, transport, storage and disposal are critical.
For many years the production of EPS has been used halogenated ozone depleting substances (ODS) responsible for man-made chemical ozone depletion.
The environmental impact of transporting and storing EPS is high because its typically manufactured in blocks with a reduced density. For just a 250 m2 house a 40ft container full of EPS blocks is required…
EPS is one of the less reclaimed plastic materials  because it is uneconomical to recycle EPS and it is expensive to collect and dispose.
Reason #4: EPS used in waffle slabs does not come from recycling
EPS can be recycled but the quality of the product obtained from recycling is not as good as when it is produced out of virgin resins and it is considered unsuitable for use in foundations.
Reason #5: EPS insulation performance is questionable
There is a minimal overall increase in R-value for systems using polystyrene blocks above a plain slab-on-ground floor  and EPS  (as well as XPS ) insulation performance deteriorates because of moisture absorption.
CPEng(NZ, AU) Dott.Ing(ITA) M.Eng(Hons)
CEO and Founding Director of Cresco
 https://www.environment.gov.au/system/files/pages/9014ac31-f832-48bd-85b9-f02d8ef70fbe/files/waffle-pod.pdf  https://www.theguardian.com/sustainable-business/2014/aug/27/styrene-carcinogen-brands-polystyrene-foam-food-packaging  Email 27/09/16 received from International Team Ministry for the Environment (NZ)  https://issuu.com/edicomedizioni/docs/wwf_polistirolo  http://www.reclaim.co.nz/productitems.php?id=anytime4908294936a39  http://www.buildmagazine.org.nz/articles/show/perimeter-insulation/  https://www.youtube.com/watch?v=aiH4zXEE60g; https://www.youtube.com/watch?v=8WBDt0Gtdtw&t=0s  https://www.youtube.com/watch?v=osPWryFMfGM